package org.example.y24.m10;

import java.util.Scanner;

public class Test3 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        System.out.println(fun(n));
    }

    private static int fun(int n) {
        if (n == 1 || n == 2){
            return 1;
        }
        return fun(n - 1) + fun(n - 2);
    }
}
